Williams was homeschooled through grade 12 and started college at age 15. Brynn has a very large family most of which are well-known, Brynn is the great-granddaughter of jazz legend Bobby Tucker Jr. She is the niece of Pittsburgh Steelers' head coach Mike Tomlin and is the sister of Jazzy Williams who starred in Nickelodeon's TV show "Wits Academy".
Brynn sang her first solo at age 2, and by age 6 she was performing professionally throughout Maryland. Williams made her Broadway debut as a sewer kid in "Chitty Chitty Bang Bang," and by age 12 she became the youngest person in history to win Broadway's historical Gypsy Robe. Shen then went onto go in many other Broadway productions. Her Broadway career flourished as she performed in the original Broadway casts of "In My Life," "How the Grinch Stole Christmas," "13 the Musical," and "Bye, Bye Birdie--the revival," and David Bowie's last project "Lazarus." Her latest Broadway performance as of October 10, 2020 was being a swing and an understudy for Sandy Cheeks in Spongebob Squarepants, The Broadway Musical from December 4, 2017 to July 29, 2018.